Back titration with mercuric nitrate in alkaline medium

Summary Small amounts of bismuth in the order of 100 g up to 25 mg were potentiometrically determined by back titration with mercuric nitrate in alkaline media. The method gives highly accurate results and is further successfully applied for analysis of pairs of bismuth together with one of the cations of calcium, copper, cadmium, zinc, manganese, nickel, lead, aluminium and lanthanum.See also Z. analyt. Chem. 161, 401 (1958); 163, 81 (1958).     

Extraction,Separation and Spectrophotometric Determination of Bismuth(III) Using 1(4′-Bromophenyl) 4,4,6-Trimethyl (1H,4H)-Pyrimidine-2-Thiol

Abstract

The operating conditions for the spectrophotometric determination of bismuth(III) with 1-(4′-bromophenyl)-4,4,6-trimethyl-(1H,4H)-pyrimidine-2-thiol (4′bromo PTPT) as a ligand by a liquid-liquid extraction technique are presented. In acidic conditions bismuth(III) forms a yellow complex with the ligand which can be extracted in chloroform with an absorption maxima at 410 nm. The molar absorptivity is 1.5×10⁴ l mole^?1 cm^?1 and Sandell's sensitivity is 14.3 ng cm^?2. The difference in the absorbance between the chloroform blank and bismuth(III) sample increases linearly in the concentration range 2-14 ppm at 0.3 M hydrochloric acid. The proposed method is extremely sensitive, rapid, reproducible and has been satisfactorily applied to the determination of trace amounts of bismuth(III) in synthetic mixtures, alloys and pharmaceutical formulations and also provides binary separation of bismuth(III) from selenium, tellurium, lead, antimony, copper and gold. The overall process of extraction and determination takes about 15 to 20 min.     

A Radiochemical Method for Selective Determination of Traces of Lead

Abstract

A very simple and rapid radiochemical method for the determination of 0.01–1 meg of lead has been developed. It consists of adding carrier-free ²¹²Pb to the analysed sample, followed by shaking with a standard lead diethyldithiocarbamate solution in carbon tetrachloride. The amount of non-active lead in the sample is determined from activities of the organic and aqueous phases. A 10-fold excess of bismuth and more than 50–100-fold excess of other metals extractable as diethyldithiocarbamates do not interfere in the determination.     

Stability-indicating high performance thin layer chromatographic determination of sulfanilamide in human urine

A simple, sensitive, selective, precise and stability-indicating high-performance thin-layer chromatographic (HPTLC) method was developed and applied to human urine for the densitometric determination of sulfanilamide. A mixture of chloroform-ethyl acetate-xylene (2.5: 4.0: 1.0, v/v/v) was used as a mobile phase. The system was found to give compact spots for sulfanilamide (retardation factor, R _f = 0.21±0.02). The linear regression analysis data for the calibration plots showed good linear relationship with r ² = 0.9970 ± 0.0003 and r ² = 0.9947 ± 0.020 within the concentration range of 50–250 ng per spot and 100–1000 ng per spot with respect to peak area, respectively. The limit of detection (LOD) and quantification (LOQ) were 8 and 25 ng per spot, respectively. Sulfanilamide was subjected to acid and alkali hydrolysis, oxidation, dry heat and wet heat treatment. According to the International Conference on Harmonization (ICH) guidelines the method was validated for precision, recovery and robustness. The ultraviolet (UV) spectra of the degradation products which had different spectra from sulfanilamide were also recorded. The article is published in the original.     

The Determination of Trace Amounts of Phosphate in Natural Water by Flow Injection Fluorimetry

Abstract

A new method is suggested for the determination of trace amounts of phosphate by flow injection fluorimetry, based on the principle that molybdophosphate could quench the fluorescence of Rhodamine 6G. The fluorescence is excited at 350 nm and measured at 550 nm. The calibration graph is linear up to 100 ng/ml phosphorus concentration and the detection Unit is 1.9 ng/ml. The present method has been applied to the determination of soluble phosphorus in natural water samples, the recoveries were in the range of 92 – 102 %. The sampling rate is 120 samples per hour.     

Studies with the Selectrode: Determination of Oxalate Ion Activity

Abstract

A solid state oxalate sensor is reported utilizing a commercial ion-selective electrode, the Selectrode^TM. Comparative measurements in aqueous solution of similar carboxylate ions and common inorganic anions, indicates appreciabl'e selectivity for oxalate. The Selectrode^TM was activated with a mixture of silver sulphide, lead sulphide, and lead oxalate.     

Application of the Bismuth Film Electrode for Voltammetric Determination of Titanium Using Ti(IV)‐Oxalate‐Chlorate Catalytic System

The catalytic voltammetric protocol for the determination of titanium at a bismuth film electrode is presented. The method is based on the reduction of the Ti(IV)‐oxalate complex to Ti(III)‐oxalate in an acidic solution. It was proven that the addition of KClO₃ causes rapid oxidation of Ti(III)‐oxalate and, subsequently, an increase of the reduction peak current of Ti(IV) at the bismuth film electrode. Parameters that influence the Ti response, including the film preparation, solution pH, oxalate acid and chlorate concentrations, were optimized. The exploitation of the bismuth film electrode under the optimized conditions yielded a stable response for titanium, with high sensitivity (12.5 μA μM^?1), good precision (RSD=5.0%) and a low detection limit (1×10^?8 M).     

Ionophore Based Bismuth Film Electrode for Lead

Abstract

A Nafion/ionophore, 4-tert-butylcalix[4]arene-tetrakis(N,N-dimethylthioacetamide) composite coated and bismuth film modified glassy carbon electrode. (GC/NA-IONO/BiFE) was described to determine trace lead sensitively and selectively. The characteristics of such modified GC/NA-IONO/BiFE were studied by scanning electron microscopy and cyclic voltammetry. The influence of various experimental parameters upon the stripping lead signal at the GC/NA-IONO/BiFE was explored. Under the optimized conditions, the differential pulse voltammetric stripping response is highly linear over the 0.1–8.0 nM lead range examined (180 s preconcentration at ?1.2 V), with a detection limit of 0.044 nM and good precision (RSD = 5.4% at 0.5 nM). Also applicability to seawater samples was demonstrated at such modified electrode. The high selectivity of ionophore coupled with the excellent electrochemical characteristics of bismuth endow the GC/NA-IONO/BiFE a promising and robust tool for monitoring of trace lead rapidly and precisely.     

Luminescence Determination of Europium in High-Purity Yttrium and Gadolinium Oxides

ABSTRACT

A luminescence spectrometric method was developed for the determination of ultratrace amounts of europium (down to 1×10^?10 M) in high-purity yttrium and gadolinium oxides. This is based on the enhanced luminescence of europium thenoyltrifluoroacetone (TTA)-Tri-n-octyl phosphine oxide (TOPO)-Triton X-100 in the presence of terbium. The luminescence intensity is linear with europium concentration in the range 1×10^?9 to 1×10^?6 M under the recommended conditions. The optimized procedure is successfully utilized for the determination of ultratrace amounts of europium in yttrium and gadolinum oxides.     

Flow Injection On-Line Two-Stage Solvent Extraction Preconcentration Coupled with Et-Aas for Determination of Bismuth in Biological and Environmental Samples

ABSTRACT

A robust flow injection/sequential injection(FIA/SIA) on-line two-stage solvent extraction separation/preconcentration procedure coupled to electrothermal atomic absorption spectrometry (ETAAS) is described and demonstrated for the determination of trace-levels of bismuth. In 1-4% (v/v) nitric acid medium, diethyldithiophosphate (DDPA) chelates bismuth and the chelating complex formed is extracted into isobutyl methyl ketone (IBMK), which is separated from the aqueous phase by means of cavity gravitational phase separation. Both single and two-stage separations are used. In each case, 40 μl of the concentrate is entrapped and metered in a loop, and subsequently delivered via air-segmentation into a pyrolytically coated graphite tube. The ETAAS determination is performed in parallel with the preconcentration process of the ensuing sample. Enrichment factors of 17.8 and 31.5, detection limits of 12 ng 1^?1 and 10.5 ng 1^?1 for single and two-stage extractions, respectively, along with a sampling frequency of 13 h^?1 were obtained with 100 s of sample loading time at a sample flow rate of 5.4 ml min^?1. The relative standard deviations were 2.8% and 1.9% for single and two-stage extractions, respectively. The procedure was validated by determining the bismuth content in a certified reference material and i8543220 human urine samples.     

Flow Injection On‐line Preconcentration Coupled with Hydride Generation Atomic Fluorescence Spectrometry for Ultra‐Trace Amounts of Bismuth Determination in Biological and Environmental Water Samples

Abstract

A simple and sensitive flow injection on line separation and preconcentration system coupled to hydride generation atomic fluorescence spectrometry (HG‐AFS) was developed for ultra‐trace bismuth determination in water and urine samples. The preconcentration of bismuth on a nylon fiber‐packed microcolumn was carried out based on the retention of bismuth complex with Bismuthiol I. A 15% (v/v) HCl was introduced to elute the retained analyte complex and merge with KBH₄ solution for HG‐AFS detection. Under the optimal experimental conditions, an enhancement factor of 20 was obtained at a sample frequency of 24/h with a sample consumption of 13.0 ml. The limit of detection was 2.8 ng/l and the precision (RSD) for 11 replicate measurements of 0.1 µg/l Bi was 4.4%.     

Synthesis of basic bismuth(III) oxalate by precipitation from nitrate solutions

Conditions were determined in which basic bismuth oxalate of composition BiC₂O₄(OH) can be obtained by direct precipitation upon addition of oxalic acid from nitrate solutions used in production of bismuth compounds. The composition of the compound was confirmed by X-ray phase and chemical analyses, IR and Raman spectroscopy, and thermogravimetry. Electron microscopy was used to examine the effect of the composition of the reaction medium and temperature on the morphology of the product being obtained. It was shown that β-Bi₂O₃ can be obtained in oxidative thermolysis of basic bismuth oxalate, depending on its morphology.     

Electrothermal Vaporization of Trace Gallium via In SITU Alkylation for Inductively Coupled Plasma Atomic Emission Spectrometry

Abstract

A sample introduction method based on alkylation of the analyte was proposed for introducing trace gallium into inductively coupled plasma for atomic emission spectrometry. By using 10 μl of a sample solution with 15 μl of a 0.9 mol 1^-1 solution of ethylmagnesium bromide in tetrahydrofuran as alkylating reagent, a detection limit of 1.9 ng of gallium was obtained and the calibration graph was linear with the amount of gallium up to 100 ng. The relative standard deviation (n = 10) was 2.0% when 10 ng of gallium was present in the sample.     

Disposable Bismuth Oxide Screen Printed Electrodes for the High Throughput Screening of Heavy Metals

We present a simplified approach for the trace screening of toxic heavy metals utilizing bismuth oxide screen printed electrodes. The use of bismuth oxide instead of toxic mercury films facilitates the reliable sensing of lead(II), cadmium(II) and zinc(II). A linear range over 5 to 150 μg L^?1 with detection limits of 2.5 and 5 μg L^?1 are readily observed for cadmium and lead in 0.1 M HCl, respectively. Conducting a simultaneous multi‐elemental voltammetric detection of zinc, cadmium and lead in a higher pH medium (0.1 M sodium acetate solution) exhibited a linear range between 10 and 150 μg L^?1 with detection limits of 5, 10 and 30 μg L^?1 for cadmium, lead and zinc respectively. The sensor is greatly simplified over those recently reported such as bismuth nanoparticle modified electrodes and bismuth film coated screen printed electrodes. The scope of applications of this sensor with the inherent advances in electroanalysis coupled with the negliable toxicity of bismuth is extensive allowing high throughput electroanalysis.     

Sequential Extraction-Spectrofluorimetric Determination of Lead and Mercury Using Cryptand Ethers

Abstract

A spectrofluorimetric method for the determination of ultratrace amounts of lead and mercury is described based on the sequential extraction of the ternary ion-association complexes formed between the cation, a cryptand as the ligand and eosin as counter ion. A linear working range from the detection limit (9 ng/ml) to 250 ng/ml of lead and 12 ng/ml of mercury was obtained.

The relative standarddeviation was 3.5 % – 2.1 %. We propose that this method could be used routinely to control lead and mercury simultaneous.     

A Direct and Sensitive Method for the Determination of Salicylamide in Microplasma Samples by High-Performance Liquid Chromatography Using Fluorescence Detection

Abstract

A quantitative analysis of salicylamide in microplasma volumes by high-performance 1iquid chromatography using fluorescence detection is reported. The procedure is extremely simple and very rapid, involving the direct introduction of the plasma sample on the HPLC column. The assay procedure is linear over the concentration range studied, 0–100 ng/ml with correlation coefficient for the linear regression, r = 0.998. This assay procedure enables the detection of salicylamide as low as 5.0 ng/ml in plasma, using sample volume of 100 μl.     

Assessment of Lead and Cadmium in Canned Foods by Square-Wave Anodic Stripping Voltammetry

Abstract

This work reports the simultaneous determination of lead and cadmium in canned foods samples using square-wave anodic striping voltammetry (SWASV) on a bismuth film electrode (BiFE). The metal ions and bismuth were simultaneously deposited by reduction at ?1 V on a rotating carbon-paste disk electrode. Then, the preconcentrated metals were oxidized by scanning the potential of the electrode from ?1 to ?0.4 V using a square-wave waveform. The electrode displayed excellent linear behavior in the examined concentration range, from 5 to 150 µg/L of cadmium and lead (r² = 0.999 for both). Using the optimized conditions, the limits of detection were 0.27 µg/L for cadmium and 0.35 µg/L for lead. The reproducibility of the proposed sensor, evaluated in terms of relative standard deviation (RSD), were 5.8% and 3.7% of Cd and Pb, respectively for five measurements. Finally, the system based on BiFEs combined with rotating disk electrode was applied to determination of lead and cadmium in canned food samples. The results obtained were validated by inductively coupled plasma optical emission spectroscopy (ICP-OES).     

Seperations involving sulphides : Separation of alkaline earth metals from some elements that form sulphides

It has been shown that 2N sodium sulphide reagent can be used efficiently for separating. 1.Barium from rhenium, platinum, gold, bismuth, palladium, lead or cadmium. 2.Strontium, calcium and magnesium from rhenium, platium, gold, mercury, bismuth, palladium, lead or cadmium     

Fluorimetric determination of calcium by ion-pair extraction with cryptand 2.2.1 and eosin

A fluorimetric study on the extraction of calcium into 1,2-dichloroethane as an ion-pair, formed between the cryptand 2.2.1-calcium complex and the eosinate anion, is described. Optimum conditions for extraction are established and a new fluorimetric determination of ultratraces of calcium is proposed. A linear working range from 1.5 ng ml^–1 (detection limit) to 100 ng ml^–1 of calcium and a relative standard deviation of ± 2.9% at the 70 ng ml^–1 level are obtained. The equilibrium constants involved in the extraction process have been calculated and refined by the Letagrop-DISTR program. The proposed method has been tested for the direct determination of calcium in sugars.     

Diallyldithiocarbamidohydrazine (Dalzin) as an analytical reagent

Summary It has been observed that mercury can be quantitatively precipitated by Diallyldithiocarbamidohydrazine (Dalzin) at a p_H of 3–3.5. It has been separated from nickel, zinc, lead, copper, cadmium and bismuth. The latter three have been kept in solution with the help of EDTA.Part. II: Dutt, N. K., and K. P. Sen Sarma: Anal. chim. Acta (Amsterdam) 15, 102 (1956); cf. Z. analyt. Chem. 155, 353 (1957).